Expanded metal lath



March 9, 1943. g; ERSMAN 3,313,533

EXPANDED METAL LATH Original Filed May 29, 1939- INVENTOR Patented Mar. 9, 1943 UNITED STATES A'l NT OEFEQE EXPANDED METAL LATH Harvey M. Gersman, New York, N. Y., assignor to Ferrex Corporation, New York, N. Y., a corporation of Delaware Claims. (Cl. 72-117) This application is a division of my co-pending application Serial Number 276,316, filed May 29, 1939.

This invention relates to improvements in expanded metal lath.

Various of the processes heretofore proposed for the manufacture of lath of the character referred to have involved angular displacement. of the strands as an incident to the expansion of the slitted blanks. Such displacement increases substantially the size of the openings defined by the strands as the latter are caused to assume positions which are edgevlise with respect to the plane of the sheet. The relative large size of the openings and the angularity of the strands have the objection that only a slight resistance is offered to the passage of plaster through the openings. Hence, in order to avoid the Waste which would otherwise occur, it has been the practice to apply the plaster in coats, the initial or scratch coat being relatively thin and having as its primary purpose the filling of the openings to prevent passage through them of the material of the subsequently applied heavy or browning coat.

The principal object of the present invention is to overcome the above objection, this object contemplating a lath characterized by a strand arrangement which will render a scratch coat unnecessary and enable a substantial saving in plaster and in the time required to apply the latter.

A further object is to provide a lath having a substantial measure of stifiness.

The invention is illustrated in the accompanying drawing in which:

Figure 1 is a plan view of apparatus for slitting and shaping blanks suitable for expansion into lath embodying the features of the invention.

Figure 2 is a side elevation of the apparatus.

Figures 3, 4 and 5 are enlarged views taken along lines 3-3, 6-4 and 55, respectively, of Figure 1.

Figure 6 is a fragmentary view in plan of thelath.

Figure 7 is an enlarged section taken along line 'l-'i of Figure 6.

Figure 8 is an enlarged fragmentary view in plan of the lath.

In the manufacture of the lath a sheet in of suitable gauge is passed through a pair of slitting rolls I l and i2 in which it is formed with parallel longitudinally extending rows of slits. The latter provide strands 13 which are connected by extensions l3Ct and bonds l4, the slits 15 of alternate rows being in staggered or breakjoint relation with respect to the slits it of intermediate rows and preferably being shorter than the latter.

From the rolls H and G2 the sheet passes to a pair of forming rolls l1 and 18, one of which is shaped to provide annular flutes it which correspond in number to the strands i3 and the other of which is formed with mating embossments 26. The crests of the flutes it engage the linear portions of the sheet which include the long slits while the. embossments 2i} force the longitudinally extending zones between the long slits into the flutes. The strands i3 and the connecting portions containing the short slits are thereby arched While median creases 2| which are collinear with the long slits are formed in the bonds I l.

Upon emerging from the forming rolls the sheet is expanded to the desired width, preferably by the application of forces which act parallel to the plane of the sheet. This is in accordance with conventional practice and apparatus of standard design (not shown) may, therefore be employed. As the sheet is stretched in the manner described, the bond sections at the opposite sides of the creases 2! fold and the strand extensions at the opposite sides of the short slits pivot away from one another and bend at their points of juncture with the strands and bonds, the angular displacement of the eX tensions being supplemental to, and hence being facilitated by, the original small ,displacement effected by the forming rolls. The extensions at each end of each strand turn in opposite directions, hence, in so far as any twisting effect upon the strands is concerned, counteract one another. As a result the strands move edgewise as they are separated in the manner described and maintain their original fiatwise or widthwise positions in the sheet, that is to say positions in which, in a widthwise direction, they extend in the direction of the plane of the sheet.

From the foregoing it will be apparent that the lath produced in accordance with the invention is characterized by strands which are arranged flatwise or widthwise in the plane of the sheet. The lath has the advantage, therefore, that while it may be expanded to the same degree as conventional diamond mesh lath, the distance between strands is substantially less, so much so that the necessity of a scratch coat is avoided. In this connection it will be noted that the only parts of the sheet presented edgewise are the bonds and the strand extensions, that is to say those parts which define the short slits. The openings which are produced when these parts are deformed in the manner described, however, are relatively small and represent only a small part of the total area. They are, therefore, not objectionable.

The slitting of the blank and the pre-shaping of the strands and connecting bonds are performed by rolls in a continuous operation. High speed production is thus insured. The arching of the strands not only insures angular displacement of the extensions in the proper direction but also has the further advantage that a substantial measure of stifiness is imparted to the sheet.

I claim as my invention:

1. Expanded sheet metal lath comprising par allel rows of strands which widthwise extend in the direction of the plane of the sheet and have extensions which are spaced longitudinally along the strands, which diverge for a portion of their extent and which are joined at their outer ends between adjacent strands to form bonds, the diverging portions of said extensions being deflected in opposite directions toward edgewise positions and being bent at their points of juncture with said strands and bonds.

2. Expanded sheet metal lath comprising parallel rows ofstrands which widthwise extend in the direction of the plane of the sheet and have extensions which are spaced longitudinally along the strands, which diverge for a portion of their extent and which are joined at their outer ends between adjacent strands to form bonds, said bonds being folded along median lines while the diverging portions of said extensionS are deflected in opposite directions toward edgewise positions and are bent at their points of juncture with said strands and bonds.

3. Expanded sheet metal lath comprising parallel rows of arched strands which widthwise extend in the direction of the plane of the sheet and have extensions which are spaced longitudinally along the strands, which diverge for a portion of their extent and which are joined at their outer ends between adjacent strands to form bonds, said bonds being folded along median lines while the diverging portions of said extensions are deflected in opposite directions and are bent at their points of juncture with said strands and bonds.

4. Expanded sheet metal lath comprising parallel rows of strands which widthwise extend in the direction of the plane of the sheet and have extensions which are spaced longitudinally along the strands, which diverge for a portion of their extent and which are joined at their outer ends between adjacent strands to form bonds, the diverging portions of said extensions being deflected in opposite directions and being bent at their points of juncture with said strands and bonds.

5. Expanded sheet metal lath comprising parallel rows of arched strands which widthwise extend in the direction of the plane of the sheet and have extensions which are spaced lon itudinally along the strands, which diverge for a portion of their extent and which are joined at their outer ends between adjacent strands to form bonds, the diverging portions of said extensions being deflected in opposite directions and bein bent at their points of juncture with said strands and bonds.

HARVEY M. GERSMAN. 

